Damage detection on a prestressed concrete bridge and RC beams using dynamic system identification

In the framework of developing a health monitoring system for civil engineering structures, vibration analysis has proven to be a useful tool. Vibration monitoring of civil engineering structures (e.g. bridges, buildings, dame) has gained a lot of interest over the past few years, due to the relative ease of instrumentation and the development of new powerful system identification techniques. The damage assessment step consists of relating the dynamic characteristics to a damage pattern of the structure. The presented technique makes use of the calculation of modal bending moments and curvatures to derive the bending stiffness at each location. The basic assumption is that damage can be directly related to a decrease of stiffness in the structure. Eigenfrequencies are sensitive damage indicators. Modal curvatures seem to be more sensitive to local damage than the modal displacements. The technique is validated on a prestressed concrete bridge and on reinforced concrete beam, which were both gradually damaged and tested extensively.